For your sanity, just assume that the shooter's right hand is on the grip, his left is holding the forward grip/barrel/whatever, and the ejection port is to the left side of the gun, where it is harmlessly ejecting into his buddy's neck.

Even long after the fall of Space-Rome (proper name to be given later), the hundreds of remaining warships of the Legio Mortis still continued to travel through space, typically obliterating anything that attempted to board them and take the valuable Old Tech hidden within.